The centrifuge rotor arrangement such as described in United States Patent Application Ser. No. 15,911, filed Feb. 28, 1979 and U.S. Pat. No. 4,314,523 (Boeckel et al.) issued Feb. 9, 1982 is adapted to deposit particles, such as cells, suspended in a liquid medium known as a supernatant onto a suitable deposition surface, such as microscope slide, so that further examination of the cells may occur. The rotor arrangement utilizes a removable chamber block mountable therein. Each chamber block is provided with an inlet channel for receiving a sample containing a supernatant having particles suspended therein and an outlet channel through which the particles and supernatant are moved under the influence of centrifugal force onto the deposition surface. A supernatant withdrawal conduit, or cannula, extends through the body of the chamber block to collect supernatant by drawing the same under suction in a rearward direction from the deposition surface.
U.S. Pat. No. 4,306,514 (Bouclier) issued Dec. 22, 1981 and U.S. Pat. No. 4,327,661 (Boeckel) issued May 4, 1982 disclose chamber blocks having a deflection baffle disposed within the block and arranged such that supernatant withdrawn through the withdrawal conduit from the vicinity of the slide is deflected into a collection receptacle or into a collection vial introduced into an opening formed in the chamber block.
Observations have indicated the possibility that a sample of particles and supernatant introduced into the inlet channel may run through the block into a collection vial before the particles have had an opportunity to deposit onto the deposition surface. This possibility is enhanced if withdrawal suction is applied to the block before the particles have been subjected to the centrifugal force field. Furthermore the possibility has been raised that once collected in the vial the supernatant may be urged to reenter the block. Thus, it may be necessary to require that an operator remove supernatant previously collected in order to prevent reentry of the already withdrawn supernatant into the cannula. Both these possibilities are also believed to be disadvantageous.
In view of the foregoing it is believed advantageous to provide a chamber block wherein the possibility of sample run-through or supernatant reentry is minimized.